holocytochrome c synthase
Last updated 26 Sept 2025
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The HCCS gene carries instructions for producing an enzyme called holocytochrome c-type synthase. This enzyme is active in many tissues of the body and is found in the mitochondria, the energy-producing centers within cells.
Normal function
The HCCS gene carries instructions for producing an enzyme called holocytochrome c-type synthase. This enzyme is active in many tissues of the body and is found in the mitochondria, the energy-producing centers within cells.
Within the mitochondria, the holocytochrome c-type synthase enzyme helps produce a molecule called cytochrome c. Specifically, holocytochrome c-type synthase is involved in a reaction that adds an iron-containing molecule called heme to make mature cytochrome c, also called holocytochrome c, from a precursor form called apocytochrome c.
Cytochrome c is involved in a process called oxidative phosphorylation, by which mitochondria generate adenosine triphosphate (ATP), the cell's main energy source. It also plays a role in the self-destruction of cells (apoptosis).
Conditions referring to this gene or chromosome
Other names
CCHL
CCHL_HUMAN
DKFZp779I1858
holocytochrome c synthase (cytochrome c heme-lyase)
MCOPS7
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Further reading and references
- holocytochrome c synthase; MedlinePlus, National Library of Medicine.
- D'Alessio AM, Indrieri A, Vitiello G, Morleo M, Schelley S, Enns GM, Passarelli C, Tammaro R, Tiranti V, Peron C, Deb W, Novelli A, Isidor B, Iolascon A, Franco B. Revisiting LSDMCA: male lethality escape and genotype-phenotype correlations. Eur J Hum Genet. 2026 Jul;34(7):972-979. doi: 10.1038/s41431-026-02098-7. Epub 2026 Apr 21.
- Indrieri A, Conte I, Chesi G, Romano A, Quartararo J, Tate R, Ghezzi D, Zeviani M, Goffrini P, Ferrero I, Bovolenta P, Franco B. The impairment of HCCS leads to MLS syndrome by activating a non-canonical cell death pathway in the brain and eyes. EMBO Mol Med. 2013 Feb;5(2):280-93. doi: 10.1002/emmm.201201739. Epub 2013 Jan 22.
- Indrieri A, Franco B. Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA): An Unconventional Mitochondrial Disorder. Genes (Basel). 2021 Feb 11;12(2):263. doi: 10.3390/genes12020263.
- Indrieri A, van Rahden VA, Tiranti V, Morleo M, Iaconis D, Tammaro R, D'Amato I, Conte I, Maystadt I, Demuth S, Zvulunov A, Kutsche K, Zeviani M, Franco B. Mutations in COX7B cause microphthalmia with linear skin lesions, an unconventional mitochondrial disease. Am J Hum Genet. 2012 Nov 2;91(5):942-9. doi: 10.1016/j.ajhg.2012.09.016.
- Morleo M, Franco B. Microphthalmia with Linear Skin Defects Syndrome. 2009 Jun 18 [updated 2018 Jul 26]. In: Adam MP, Bick S, Mirzaa GM, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Available from http://www.ncbi.nlm.nih.gov/books/NBK7041/
- Prakash SK, Cormier TA, McCall AE, Garcia JJ, Sierra R, Haupt B, Zoghbi HY, Van Den Veyver IB. Loss of holocytochrome c-type synthetase causes the male lethality of X-linked dominant microphthalmia with linear skin defects (MLS) syndrome. Hum Mol Genet. 2002 Dec 1;11(25):3237-48. doi: 10.1093/hmg/11.25.3237.
- Reis LM, Basel D, Bitoun P, Walton DS, Glaser T, Semina EV. Novel Intragenic and Genomic Variants Highlight the Phenotypic Variability in HCCS-Related Disease. Genes (Basel). 2024 Dec 20;15(12):1636. doi: 10.3390/genes15121636.
- van Rahden VA, Fernandez-Vizarra E, Alawi M, Brand K, Fellmann F, Horn D, Zeviani M, Kutsche K. Mutations in NDUFB11, encoding a complex I component of the mitochondrial respiratory chain, cause microphthalmia with linear skin defects syndrome. Am J Hum Genet. 2015 Apr 2;96(4):640-50. doi: 10.1016/j.ajhg.2015.02.002. Epub 2015 Mar 12.
- van Rahden VA, Rau I, Fuchs S, Kosyna FK, de Almeida HL Jr, Fryssira H, Isidor B, Jauch A, Joubert M, Lachmeijer AM, Zweier C, Moog U, Kutsche K. Clinical spectrum of females with HCCS mutation: from no clinical signs to a neonatal lethal form of the microphthalmia with linear skin defects (MLS) syndrome. Orphanet J Rare Dis. 2014 Apr 15;9:53. doi: 10.1186/1750-1172-9-53.
- Wimplinger I, Morleo M, Rosenberger G, Iaconis D, Orth U, Meinecke P, Lerer I, Ballabio A, Gal A, Franco B, Kutsche K. Mutations of the mitochondrial holocytochrome c-type synthase in X-linked dominant microphthalmia with linear skin defects syndrome. Am J Hum Genet. 2006 Nov;79(5):878-89. doi: 10.1086/508474. Epub 2006 Sep 6.
- Wimplinger I, Shaw GM, Kutsche K. HCCS loss-of-function missense mutation in a female with bilateral microphthalmia and sclerocornea: a novel gene for severe ocular malformations? Mol Vis. 2007 Aug 27;13:1475-82.
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